Microwave oven



FIG. 1 is a perspective view of the microwave oven showing my new design;

FIG. 2 is a front elevational view;

FIG. 3 is a rear elevational view;

FIG. 4 is a top plan view;

FIG. 5 is a bottom plan view;

FIG. 6 is a right side elevational view; and

FIG. 7 is a left side elevational view. 

The ornamental design for a microwave oven, as shown and described. 